"use client";

import { useEffect, useState } from "react";
import { usePathname } from "next/navigation";

import { syncCommissionPush } from "@/components/commission/push-client";
import { Button } from "@/components/ui/button";
import { Dialog, DialogContent, DialogDescription, DialogFooter, DialogHeader, DialogTitle } from "@/components/ui/dialog";
import { Field, FieldLabel } from "@/components/ui/field";
import { Switch } from "@/components/ui/switch";

type InstallEvent = Event & { prompt: () => Promise<void>; userChoice: Promise<{ outcome: string }> };

const dismissedKey = "site-entry-prompt-dismissed";
const dontAskAgainKey = "site-entry-prompt-dont-ask-again";

function isPromptDismissed() {
  return sessionStorage.getItem(dismissedKey) === "1" ||
    localStorage.getItem(dontAskAgainKey) === "1";
}

function isInstalled() {
  return window.matchMedia("(display-mode: standalone)").matches ||
    (navigator as Navigator & { standalone?: boolean }).standalone === true;
}

export function SiteEntryPrompt() {
  const pathname = usePathname();
  const [open, setOpen] = useState(false);
  const [installed, setInstalled] = useState(false);
  const [installEvent, setInstallEvent] = useState<InstallEvent | null>(null);
  const [permission, setPermission] = useState<NotificationPermission | null>(null);
  const [busy, setBusy] = useState(false);
  const [error, setError] = useState("");
  const [dontAskAgain, setDontAskAgain] = useState(false);

  useEffect(() => {
    // Commission pages have their own prompt, tied to the signed-in user's messages.
    if (pathname !== "/") {
      const frame = requestAnimationFrame(() => setOpen(false));
      return () => cancelAnimationFrame(frame);
    }

    const installedNow = isInstalled();
    const ios = /iPad|iPhone|iPod/.test(navigator.userAgent) ||
      (navigator.platform === "MacIntel" && navigator.maxTouchPoints > 1);
    const canNotify = window.isSecureContext && "Notification" in window &&
      "PushManager" in window && "serviceWorker" in navigator;

    const frame = requestAnimationFrame(() => {
      setInstalled(installedNow);
      setPermission(canNotify ? Notification.permission : null);
      if (!isPromptDismissed() &&
        ((ios && !installedNow) || (canNotify && Notification.permission === "default"))) {
        setOpen(true);
      }
    });

    const beforeInstall = (event: Event) => {
      event.preventDefault();
      setInstallEvent(event as InstallEvent);
      if (!isPromptDismissed()) setOpen(true);
    };
    const onInstalled = () => {
      setInstalled(true);
      setInstallEvent(null);
      if (!canNotify || Notification.permission !== "default") setOpen(false);
    };
    window.addEventListener("beforeinstallprompt", beforeInstall);
    window.addEventListener("appinstalled", onInstalled);
    return () => {
      cancelAnimationFrame(frame);
      window.removeEventListener("beforeinstallprompt", beforeInstall);
      window.removeEventListener("appinstalled", onInstalled);
    };
  }, [pathname]);

  function dismiss() {
    sessionStorage.setItem(dismissedKey, "1");
    setOpen(false);
  }

  function toggleDontAskAgain(checked: boolean) {
    setDontAskAgain(checked);
    if (checked) localStorage.setItem(dontAskAgainKey, "1");
    else localStorage.removeItem(dontAskAgainKey);
  }

  async function install() {
    if (!installEvent) return;
    await installEvent.prompt();
    await installEvent.userChoice;
    setInstallEvent(null);
  }

  async function enableNotifications() {
    setBusy(true);
    setError("");
    try {
      const result = await Notification.requestPermission();
      setPermission(result);
      if (result !== "granted") {
        if (!showInstall) setOpen(false);
        return;
      }

      // A signed-in commission user can receive messages immediately. Guests can
      // subscribe when they later sign in and visit their commission page.
      const response = await fetch("/api/commission/push-subscription", { cache: "no-store" });
      if (response.ok) {
        const config = await response.json() as { publicKey: string; canAdmin: boolean };
        await syncCommissionPush(config.canAdmin ? "admin" : "customer", config.publicKey);
      }
      if (!showInstall) setOpen(false);
    } catch {
      setError("เปิดการแจ้งเตือนไม่สำเร็จ กรุณาลองอีกครั้ง");
    } finally {
      setBusy(false);
    }
  }

  const ios = typeof navigator !== "undefined" &&
    (/iPad|iPhone|iPod/.test(navigator.userAgent) ||
      (navigator.platform === "MacIntel" && navigator.maxTouchPoints > 1));
  const showInstall = !installed && (ios || installEvent !== null);
  const canAskNotification = permission === "default" && (!ios || installed);

  return <Dialog open={open} onOpenChange={(next) => { if (!next) dismiss(); }}>
    <DialogContent>
      <DialogHeader>
        <DialogTitle>{showInstall ? "ติดตั้ง Buzz Guide และรับการแจ้งเตือน" : "รับการแจ้งเตือนจาก Buzz Guide"}</DialogTitle>
        <DialogDescription>
          {showInstall ?
            "เพิ่มเว็บไซต์ลงหน้าจอหลักเพื่อเปิดใช้งานได้สะดวก และรับการแจ้งเตือนเมื่อมีข้อความใหม่ใน Commission หลังเข้าสู่ระบบ" :
            "รับการแจ้งเตือนเมื่อมีข้อความใหม่ใน Commission หลังเข้าสู่ระบบ"}
        </DialogDescription>
      </DialogHeader>
      {!installed && ios && <p className="text-sm text-muted-foreground">
        บน iPhone/iPad แตะปุ่มแชร์ใน Safari แล้วเลือก ‘เพิ่มไปยังหน้าจอโฮม’ จากนั้นเปิดแอปที่ติดตั้ง
      </p>}
      {ios && !installed && <p className="text-sm text-muted-foreground">
        ติดตั้งและเปิดจากหน้าจอโฮมก่อน จึงจะเปิดการแจ้งเตือนได้บน iPhone/iPad
      </p>}
      {error && <p role="alert" className="text-sm text-destructive">{error}</p>}
      <Field orientation="horizontal">
        <FieldLabel htmlFor="site-entry-dont-ask-again">ไม่ต้องถามอีก</FieldLabel>
        <Switch id="site-entry-dont-ask-again" checked={dontAskAgain} onCheckedChange={toggleDontAskAgain} />
      </Field>
      <DialogFooter>
        <Button type="button" variant="outline" disabled={busy} onClick={dismiss}>ไว้ก่อน</Button>
        {installEvent && !installed && <Button type="button" variant="secondary" disabled={busy} onClick={() => void install()}>ติดตั้งแอป</Button>}
        {canAskNotification && <Button type="button" disabled={busy} onClick={() => void enableNotifications()}>เปิดการแจ้งเตือน</Button>}
      </DialogFooter>
    </DialogContent>
  </Dialog>;
}